So I'm trying to see if I can isolate protein and RNA from the RNeasy Minikit. I am working with about 7 mg of rat nasal epithelial tissues and therefore need an efficient way to get both RNA and proteins from the same small sample. I know they sell a DNA/RNA/protein kit from Qiagen, but it is very expensive. TRIzol is also not going to be an option because I have not had good luck isolating RNA from my samples with their methods (contamination issues and low RNA yields).

Any suggestions on how I can isolate both total protein and RNA from my rat samples using this RNeasy method (or one just as costly...or cheaper :-) ).

by the way, this protocol worked beautifully. I did make some editions though.

I find it better to add 1.5 volumes of IPA to the 1st flow through from the RNeasy column (ie from the 70% EtOH addition step). I then continue with the protocol verbatum. It saves on having to wait a day of letting your tubes sit at -20C. I was able to get RNA and whole cell lysate protein samples from the same 4-5mg chunk of nasal tissue!